Low-water alarm



(No Model.) A y W. I'. HAND. LOW WATER ALARM.

10.411.675 Patented Dec. 17, 1889 Au. mins. Phmumnpm wnhingrm. n. c

UNITED STATES PATENT OFFICE;

VILLIAM F. HAND, OF BAY CITY, ASSIGNOR OF ONE-HALF TO ANDREV VVILDMAN, OF EAST SAGINAV, MICHIGAN.

LOW-WATER ALARM.

SPECIFICATION forming part of Letters Patent No. 417,675, dated December 17, 1889.

Application liled September 1.3, 1889. Serial No. 323,840. (No model.) i

To all whom it may concern:

Be 'it known that I, WILLIAM F. HAND, a citizen of the United States, residing at Bay City, in the county of Bay and State of Michigan, have invented certain new and useful Improvements in Low-Water Alarms; and I do declare the following to be a full, clear, and exact description of the invention,.such as` will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawing, and to the letters of reference marked thereon, which forma part of this specification. l

This invention relates to improvements in low-water alarms for steam-boilers of the class in which a plug of metal fusible at the temperature ofV steam under pressure is so arranged as to be exposed to a low temperature when there is a sufciency of water in the boiler, but to be exposed to a higher or melting temperature on the water in the boiler being `at a lower than an ordinary stage, or on the surface of the water becoming lowered so as to approach a dangerous line.

The principal object of my invention is to arrange and construct a device for carrying a fusible `metallic plug, so that on a temporary displacement or lowering of the water in the boiler the metallic plug will remain in a solid condition, but on a permanent lowering` of `the water the plug will be removed and furnish a warning to the operator that the water has reached a stage that requiresimmediate attention;

The invention consists in the construction, combination, and arrangement of the device, as I shall hereinafter proceed to describe, and which will be particularly pointed out iu the claims of this specification.

The invention consist-s, further, in the combination of the parts and in the arrangement of the-same, 'whereby the time within which the plug will-be removed after the water in the boiler has reached a dangerous level' may be regulated by the operator.

The invention also consists in the combination and arrangement of the parts of the device so that they may be locked in position, whereby the operator or engineer is required to report each time the alarm may have operated. l

I illustrate my improvement in the accompanying drawing, in which the figure is a vertical central section of my improved device as attached to a steam-boiler.

Referring to the drawing, a represents the upper portion of the shell of a steam-boiler, and b are the lues.

cis a pipe passed downward through the vshell a, and is arranged with its lower end d reaching nearly to the flues b, or to a position below the ordinary water-level in the boiler, lwhile the upwardly extending portion e is passed through the lower end f of a casing g, which incloses a chamber h, the end por tion i of the pipe extending nearlyto the up per head j of the casing.

71: is a pipe passed through the upper head j,'and is arranged with its lower portion l extending downwardly beside the pipe e, and reaches nearly to the lower head f, while to the upper end of the pipe k is connected a valve fm, and to the upper part of the valve is connected by a screw-thread a plug-holder n, having a central tapering opening o, and into this ope-ning o is titted a plugp, of a metal composition which remains in the solid stat-e when exposed to a low temperature, but which, however, will melt when exposed to the ,highertemperatizre of steam under ordinary pressure. The pipe t' is provided near t-he lower head f with an opening q, while the outer end of the plug is provided with a handwheel u, with which to turn the plug.

'u isa pipe passed through the lower portion of the casing into the chamber and is provided with the valve w for blowing out the contents of the chamber whenever required.

The valve m is provided with a valve-stem' 0c, which on being turned in one direction by means of a screw-thread moves outwardly in the direction of its length for opening the valve, but must be turned in the opposite direction and move inwardly to close the valve; and fy is an opening through the stem while .e is a padlock with its U -shaped loop passed through the opening and locked in position, the opening being so located in the stem that whenthe lock is secured in position in the opening it prevents the stem from moving inwardly for closing the valve.

lVhen the device is in position for operation, the valve m is open and the water within the boiler under steam-pressure is forced up IOO the pipe c and lills the chamber and pipe k and comes in contact with the fusible plug, and on account of there being comparatively little circulation through the pipe and the chamber being located away from the boiler the water in the chamber and pipe 7c remains at a sufficiently low temperature to allow the plug to remain in a solid state; but on the water within the boiler becoming lowered, so that the lower open end of the pipe c is eX- posed to the steam, the water within the pipe at once passes by gravity into the boiler and steam rushes into the pipe and equalizes the pressure therein and in the chamber, and the water in the chamber then passes into the pipe c through the opening q, and this opening being of a limited dimension, some time must elapse before the chamber and also the pipe k are relieved of the water; but on the water having` passed out the steam of a high temperature rushes at once in from the pipe c, and coming in contact with the plug and plug-holder quickly raises the temperature thereof until the plug is fused, and the opening o being then freed from the plug the steam goes rushing through the opening, giving warning to the engineer that the water in the boiler has reached a state that requires immediate attention to prevent accident or burning of the flues, doc. On the fusible plug being removed, as stated, the operator must produce the key and unlock the padlock z and turn the valve m to close the pipe k, and the holder n may then be removed and anew plug placed in position and the holder then replaced in position, and on the water in the boiler being replenished the valve m is opened and locked in position.

It will be observed that a considerable interval of time must elapse after the steam has passed into the pipe c before the pipe k will be freed from the water to admit steam to direct contactwith the plng,and herein lies the gist of my invention, as should the water in the boiler be temporarily displaced by foaming or otherwise, t-o admit steam to the pipe c and again return before the water in the chamber has had time to pass out through the opening q, the pipe c will again fill with water and the fusible plug will remain solid, so that only a permanent lowering of the water-surface in the boiler can remove the plug. It will also be noticed that by means of the screw-plug p the area of the opening q may be regulated to allow more or less time, as may be desired, for the water in the chamber to pass out, the plug being turned so as to place the end t in position to partly close the full opening, so that a considerable interval of time will elapse between the filling of the pipe c with steam and the exposure of the fusible-metal plug to the temperature of the steam, so that the operator is sure that when the fusible plug has been melted out the waterin the boiler is in a condition that requires immediate attention, and the valve m being locked the operator must obtain a proper key to unlock the valve before the issue of steam through the opening 0 can be stopped, and this key may be placed in the o'lce of a manufactory, so that the workman in charge of the boiler must report at the office that he has allowed the water in the boiler to reach a stage lower than was entirely safe or proper.

The pipe u is used to Iblow out the contents of the chamber from time to time to remove any sediment therefrom and to keep the pipes free and open.

Vhat- I claim as my invention, and desire to secure by Letters Patent, is-

l. In a low-water alarm, the combination of a casing g, inclosing a chamber above the boiler, and a pipe c, with its upper end portion z' passed through the said casing and extending to the upper portion of the chamber and provided with an opening, as q, and having its lower portion (l passed through the boiler-'shell and reaching into the water, and apipe 7a, having its lower end portion l passed through the upper head of the said casing and extending to the bottom portion of the chamber, and having, as described, its upper end opening closed with aplug of metal fusible at the temperature of the steam in the boiler, substantially as set fort-h.

2. The combination, in a low-water alarm, of the casing inclosing a chamber, with the upper and lower vertical pipes having their adjacent end portions passed through the opposite heads of the said casing and overlaping each other, and with the lower portion of the lower pipes passed through the boilershell and reaching into the water, a valve secured to the upper end of the said upper pipe and provided with devices, as described, for locking the valve in an open position, and a plug of metal, fusible at the temperature of steam in the boiler, for closing the end opening of said upper pipe, substantially as set forth.

3. The combination, in a low-water alarm, of a casinginclosingachamber, a pipe passed through the lower head of the casing and with its upper end portion extending into the said chamber and provided with a side opening, as q, and with its lower end passed through the boiler-shell and into the water, a pipe connected to the upper head of the casing and with its lower end portion extending into the chamber and having the opening in its upper end closed by a fusible plug, as described, and the screw-threaded plug r, passed through the said casing, and with its inner end f fitted to pass into and partially close the said opening q, substantially as and for the purpose set forth.

In testimony whereof I affix my signature in presence of two witnesses.

WILLIAM F. HAND. lVitnesses:

JAS. E. THOMAS, ANDREW WILDMAN.

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